1. Field of the Invention
The present invention relates to a mobile terminal and handover method thereof. More particularly, the present invention relates to a mobile terminal performing a 2nd Generation (2G) communication function and a method for the terminal to transmit a handover complete message in a handover process.
2. Description of the Related Art
FIG. 1 is a signaling diagram illustrating operations of a mobile terminal and a base station when performing a handover procedure according to the related art. In more detail, FIG. 1 is a drawing illustrating a handover procedure of the related art between the terminal and base station in a mobile communication system.
Referring to FIG. 1, the mobile communication system includes a terminal 110 and a base station 120.
The terminal 110 sends a measurement report message to the base station 120 in step 130. The measurement report message includes identity information and channel condition information of the serving cell and neighbor cells around the terminal 110. Upon receipt of the measurement report message, the base station 120 analyzes the measurement report message to determine whether to perform handover. If the decision to handover is made, the base station 120 sends a handover command message to the terminal 110 in step 135.
The terminal 110 starts a timer in step 140 to check the retransmission period of a handover request message according to whether the channel establishment information used for the handover process is received. Next, the terminal 110 transmits the handover request message to the base station 120 in step 145. Upon receipt of the handover request message, the base station 120 sends the channel establishment information to the terminal 120 in step 150. The channel establishment information includes the identity information of the base station which is used for the handover process. Next, the terminal 110 performs handover using the received channel establishment information. Finally, the terminal 110 ends the timer in step 160 and then transmits a handover complete message to the base station in step 170.
Typically, since the handover takes place under a weak electric field condition, there is a probability that the handover will fail. Thus, there can be a situation in which the base station does not receive the handover complete message transmitted by the terminal after successful handover. However, the terminal does not know whether the handover complete message is received by the base station. In this case, the mobile terminal is likely to interpret the situation as a handover failure and, as a consequence, the ongoing communication session of the mobile terminal is broken.